The presently disclosed subject matter relates to a cardiopulmonary function evaluating apparatus and cardiopulmonary function evaluating method in which the cardiopulmonary function is evaluated by using an apparatus for measuring the volume of blood ejected with each beat of the heart.
As training for improving the cardiopulmonary function, altitude training and exercise under hypoxic conditions are performed. Usually, it is determined whether a sufficient effect is achieved in such training or not, based on a comparison before and after the training (for example, comparison between the measurement time of long-distance running conducted before the training, and that of long-distance running conducted after some time of the training), or a feeling of weariness. However, evaluation based on such a determination is not objective, and hence it is impossible to correctly acquire the effect of the training.
Patent Literature 1 discloses a technique related to a measurement index for improving the ability of the cardiopulmonary function. The cardiovascular function measuring apparatus for an athlete disclosed in Patent Literature 1 enables an athlete or the like to evaluate the comprehensive cardiovascular functions before, during, and after exercise. In the cardiovascular function measuring apparatus for an athlete, the heart rate (HR) and stroke volume (SV) of the subject are measured by using a technique in which the cardiac output is measured noninvasively and continuously for a long term (for details, see Patent Literature 2). In the cardiovascular function measuring apparatus for an athlete, then, a locus curve of the stroke volume (SV) which is measured in a process of increasing the heart rate (HR), and that of the stroke volume (SV) which is measured in a process of decreasing the heart rate (HR) are displayed on a same display unit. Thereafter, the cardiovascular function measuring apparatus for an athlete displays an evaluation of the cardiovascular function of the subject, based on the size of the area enclosed by the two locus curves. Here, the locus curves mean curves in a coordinate system in which the abscissa represents the heart rate (HR) and the ordinate represents a change of the stroke volume (SV).    (Patent Literature 1) JP-A-2007-44352    (Patent Literature 2) JP-A-2005-312947    (Non-Patent Literature 1) (Searched on Feb. 13, 2014), Internet, Nihon Kohden PWTT Principles    (Non-Patent Literature 2) Sakurai, Watanabe, “ME Hayawakari Q&A 3 Ketsuatsukei•Shinpakushutsuryokei•Ketsuryukei,” Nankodo, p. 125-127
In order to improve the cardiopulmonary ability, it is important to increase the maximum oxygen consumption. The maximum oxygen consumption is expected to be improved by increasing the stroke volume (SV). When the condition of the stroke volume (SV) (for example, relationship between the number of elapsed days in the case where training is carried out every day, and a change of the stroke volume (SV)) is known, therefore, it is possible to know the exercise effect of the subject, and the state of the cardiopulmonary function of the subject while being compared with the states of other persons.
In the cardiovascular function measuring apparatus for an athlete disclosed in Patent Literature 1, the cardiopulmonary function of the subject is evaluated by the area enclosed by the two locus curves. The area is an area in a chart in which the abscissa represents the heart rate (HR) and the ordinate represents the stroke volume (SV), and therefore indicates a value related to the cardiac output (CO). From the area, the volume of blood which is pumped from the heart in a unit of time can be known, but it is impossible to know whether the area is obtained as a result depending on the stroke volume (SV) or that depending on the heart rate (HR). In other words, the cardiovascular function measuring apparatus for an athlete evaluates the cardiovascular function by using the cardiac output (CO). In the technique, therefore, the condition of the stroke volume (SV) itself such as the amount of change of the stroke volume (SV) cannot be adequately known.